Caption: Aerial drone footage of a marine lake in Palau. These isolated lakes are often meromictic, meaning the waters do not mix, and as such become stratified. Within some of them, including this one, can be found huge numbers of stingless jellyfish (Mastigias sp.). The lake is connected to the surrounding ocean by channels in the limestone rock, but the conditions are so different that there is little exchange of animal life, allowing distinct subspecies of jellyfish to develop.